Built 6 speed Allison, delay into drive

L

LBZoom

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Apr 7, 2009
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Hey guys,
I've got a 2006 LBZ with Allison 6 speed, built it earlier this year with Suncoast parts, and a 1056 converter, billet shafts....

When we first built it, seemed to drop into drive just fine, a month or two later it started to have a delay when going into drive.... and now today you can basically count to 3 seconds before drive will engage... doesn't matter if it's warm or cold.

Shifts fine, goes into reverse fine, no check engine lights, no ghost codes...

If anyone has any idea what could be wrong I'm all ears!
 
Mike L.

Mike L.

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LBZoom said:
Hey guys,
I've got a 2006 LBZ with Allison 6 speed, built it earlier this year with Suncoast parts, and a 1056 converter, billet shafts....

When we first built it, seemed to drop into drive just fine, a month or two later it started to have a delay when going into drive.... and now today you can basically count to 3 seconds before drive will engage... doesn't matter if it's warm or cold.

Shifts fine, goes into reverse fine, no check engine lights, no ghost codes...

If anyone has any idea what could be wrong I'm all ears!
Click to expand...

Pull the sump filter and peel it open. See what's in there. Have a new filter handy.
 
L

LBZoom

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Apr 7, 2009
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Hey Mike,
Thanks for the prompt reply! I actually replaced the suction filter a few hours before my post but forgot to mention it, haven't peeled old filter open yet though.

It seems to be a little better, still has a noticeable delay engaging drive, once in a while after driving it a bit, it will give me the "range shift inhibited" message attempting to engage drive.

Would fluid type affect this or not really cause this particular type of issue?

Thanks!
 
L

LBZoom

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Apr 7, 2009
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Okay, some update...

The code that had been recurring several times last week was P2724 "solenoid E stuck open" we've pulled the valve body several times and cleaned it, made sure the mechanical valves were moving freely and they are....

As far as the actual solenoids themselves, all we've done was test resistance and they all checked out. I did notice that with the key in the run position most solenoids had 12v at the connector, but one of the smaller shift solenoids only had 7.25v, not sure if that even matters?

Goes into reverse fine still, and shifts like a dream still (provided p2724 doesn't come up again)

Every time we put it back together it still has an issue going into drive. P2724 hasn't came back yet so maybe we got it fixed, but I've only drove it a few miles at a time when testing so it maybe hasn't come back "yet." But as soon as we put it back together and put it in drive it goes into gear fine but with a short delay, once the trans heats up to about 150 you'd better not put it in park because you'll never get it back into drive, just says "range shift inhibited" sometimes you can feel a really faint "shudder" as if it's trying to engage.... and sometimes I can give it a little gas and it will actually pop into gear sometimes when it's doing this which makes me think maybe it's a low pressure issue....

I don't know if I have a solenoid that's acting like an ignition coil (when it heats up it begins to fail) or if there is something in the internal pump, or something in the ECM or TCM....

-We have swapped TCM's
-We have replaced NSBU
-Internal filter is new, external is fairly new
-solenoids' resistance checks out ok
-TCM ground is good (pins 9,69)

Thanks for any help!
 
L

LBZoom

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Apr 7, 2009
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Thanks Mike, I dropped the truck off today should have it opened up tomorrow evening... hopefully I'll find something definitive and the cause. I'll keep you posted.

Other than the obvious like a smoothed out pack of C1's, is there anything I should look for?

And also, if the C1 is worn smooth, what are possible causes? I'm only running about 550rwhp, I'm guessing maybe some debris at inital break in maybe cause some damage.... my fluid has never been discolored or smelled burnt.... guess I'll just open it up and see first.
 
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L

LBZoom

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Apr 7, 2009
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Found the issue thanks to Mike, snap ring holding the C1 pack onto the input shaft had come off partially, smoked the back half of the clutch pack. New parts will be here tomorrow and we'll be back on the road soon.

Thanks very much Mike for your help and suggestions!
 
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LBZoom

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Not sure which one was to blame, but upon initial inspection the "normal" type snap ring had lifted out slightly. With all the stress on them they had kinda overlapped in one place too.
 
Mike L.

Mike L.

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Normal type snap rings have a top and bottom. The top will have sharper edges at the opening to allow easier access with snap ring pliers.
 
L

LBZoom

New member
Apr 7, 2009
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Mike L. said:
Normal type snap rings have a top and bottom. The top will have sharper edges at the opening to allow easier access with snap ring pliers.
Click to expand...

Good to know, we're usually pretty good about checking that stuff but ya never know.

I ordered new rings, and new C1 clutches also, should all be here tomorrow.... now I just have to get an internal wire harness because when they loaded it into m truck the tranny shifted and broke that external connector...always something, thank god for good help from Sam Adams :hug:
 
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